The combustion process in gas turbine engines can peak above 2,100° C. and may typically lie in the region of 1,500° C. or higher. Such temperatures are typically higher than the melting point of the materials used for the walls of combustion chambers.
A typical gas turbine engine has a combustion chamber, which has tiles attached to the inside of a combustion liner wall so that, when the combustion chamber is in use, the tiles face towards the combustion process. Such tiles are typically ceramic coated and pedestal or impingement-effusion cooled, so as keep them at operationally safe temperatures when the combustion chamber is in use.
FIG. 1 shows an example pedestal or impingement-effusion cooled tile 1 attached to a combustion liner wall 50, as in a gas turbine engine made by the present applicant.
As shown in FIG. 1, the pedestal or impingement-effusion cooled tile 1 has an integral stud 60. To attach the pedestal or impingement-effusion cooled tile 1 to the combustion liner wall 50, the stud 60 is passed through a hole in the combustion liner wall 50 and then a nut 30 is screwed onto the stud 60.
The present inventors have observed that, in the arrangement shown in FIG. 1, effective cooling of the stud 60 is difficult to achieve, and overheating of the stud 60 can lead to material creep and loss of tension. Also, as the tile is impingement-effusion cooled, the presence of the stud 60 can disrupt the pattern of the effusion cooling holes which are formed through the tile 1.
The present invention has been devised in light of the above considerations.